Process of coating pharmaceutical forms and product thereof



United States Patent 3132 074 PROCESS or coA'fiN PHARMACEUTICAL FORMS AND PRODUCT THEREOF Edward V. Svedres, Narberth, Pa., assignor to Smith Kline & French Laboratories, Philadelphia, Pa., a corcoating for tablets which has as a main ingredient N-vinyl- S-methyl-Z-oxazolidinone polymers either alone or copolymerized with other vinyl compounds, preferably vinyl acetate. When the phrase coating composition is used it is understood that all aspects of this invention are included such as the tablet and method of coating described hereafter.

The techniques of the prior art involved in tablet coating'have undergone little change or refinement since they Were first developed. The conventional. sugar coating procedure described in the prior art usually consists of the followingsteps: (a) Waterproofing. and sealing, (b)

subcoating, (c) rounding or smoothing, (d) coloring and" finishing, and (e) polishing. This method has many disadvantages, such as for example, it is time consuming; requires skilled personnel and hence is very expensive.- This standard tablet coating procedure requires many coats before a satisfactory tablet is produced. For example, it is common practice to apply as many as 15 subcoats', 35 smoothingcoats and 40 coloring coats followed by polishing. It requires from about 15 to about 20 Working hours and up to a total time of about 65 hours.

This total time of up to 65 hours is required not only because of the plurality of coats necessary but also because the coats are put on from aqueous solution or suspension and it is necessary to evaporate the moisture between each coat. r

The gradual build up of sugar coated layers presents other disadvantages." These multiple sugarjcoatings do. not permit the coating of scored tablets, i.e., those containing grooves, or tablets with engraved monograms because the total number of coats required completely oblitcrates the groove andmonogram. Due to themultiple coatings the finishedtablet is approximately 50% greater in volume and isusually double the weight of the uncoated tablet.

- Still another disadvantage of the coating produced by the standard pan coating procedure is its low resistance to humidity. The resultant coating results indeterioration and water soluble medicaments are occasionally attacked by Water or moisture in the atmosphere or in the tablet coating mixtures. Another big drawback is that the tablet must be compressed relatively hardin order to withstand the vigorous rolling and tumbling in the coating pan. This hard compression results in a delay in dis- 3,132,074 Patentedll/lay 5, 1964 single coat or up to and including three coats. If desired, more coats may be applied however usually with little advantage. This tremendous reduction in the total number of coats required'makes it possible to coat tablets rapidly and inexpensively. The time required tocoat the tablets is reduced from days to minutes. The reduction of the number of coats also results in the production of a much smaller finished tablet. This feature adds to the popularity of the tablet because it is much easier for the patient to swallow. V

The novel coating composition of this invention results in a thin film coat. This film coat allows the imprinting or monograming and scoring of the compressed tablet. The coating is thin enough for the monogram or grooves on a compressed tablet to be seen, i.e. the compressed tablet maintains its shape in detail after coating. 7 Still another major advantage of this novel coating composition is that: anhydrous solvents are used. The elimination of the aqueouscoating solutions of the prior art reduces the drying time between coats from hours to minutes. Previous stability problems encountered due to the moisture in the tablet coating composition are now eliminated.

The major advantage of this novel coating composition is that a simple solution of the film forming compound in an anhydrous solvent is all that is necessary to form the coating composition. This film forming coating composition, when applied according to the novel process'of this invention, can accomplish sealing, subcoating, smoothing and coloring in a one step operation. The novel coating composition embraces all the above properties and a'dye may be added to impart color. When the coating composition is applied as directed in this invention it yields a hard, thin coat that does not increase disintegration time.

The coating composition of this invention is comprised of a film forming polymer containing polymerized N- vinyl-oxazolidinone as described herein dissolved in an anhydrous solvent. Other ingredients such as plasticizing agents and coloring materials maybe added to the coatpolymeric substance is defined in Cellulosechemic 13, 58

The film forming polymer is, for example, an N-vinyl- S-methyl-Z-oxazolidinone polymer containing a monomer having the general formula:

.FORMULA I H GHa-CO N H":OH2 I1 or isomers and homolo-gues thereof, n of the polymer is in excess of 50. Advantageously the polymers represented by Formula I are high polymers having a Fikentscher K-value from about 15 to 100, preferably to have a major proportion of monomeric units having I the following general formula:

FORMULA II H CHs-CO HgC (IJIO N o-ii-om bit-om-on-om n where n is in excess of 50. The preferable N-vinyl-S- methyl-2-oxazolidinone-vinyl acetate copolymer desirably has a FikentscherK-value of from about 5 to about 60. Preferably the Fikentscher Kavalue is from about 5 toabout 25. The material is a solid white resinous powder.

Most advantageously N-vinyl-S-methyl-Z-oxazolidinone copolymerized with about 50% vinyl acetate is employed as the film former for this novel coating composition. 7

Exemplary of-the anhydrous solvents used in this coating composition are nontoxic organic solvents such as lower aliphatic alcohols, for example, methyl, ethyl or isopropyl alcohol; a di lower 'alkyl ketone, preferably those having not in excess of 4 carbon atoms such as, for example, benzene, toluene, xylene; methylene chloride and chloroform. The preferred solvent is chloroform.

When coloring materialsare desired, any of the nontoxic dyes, preferably soluble in the selected solvent, such as for example, FD & C red No. 32, FD & C orange No. 2, PD & C yellow No. 3, PD & C yellow No. 4, D & C red No; 17, D & C red No. 18, D 8: C yellow No. 10, D 8; C green No. 6 and D & C violet No. 2 can be employed.

When desirable, among the plasticizing agents which may be used are dibutyl phthalate, dimethyl phthalate,

diisobutyl adipate, castor oil, mineral oil, dioctyl adipate,

dioctyl phthalate, butyl acetyl ricinoleate and butyl acetoxy s tearate. The most advantageous plasticizer is di-' octyl phthalate. p

The film forming polymer used in the coating composition of this invention is present in anamount of' from about 1% to about 15% by Weight, preferably from about 3% to about 7% by weight of the total coating composition. The nontoxic coloring agent, when employed will be in an amount to provide the desired color and shade preferably from about 0.05% to about 1% byweight of the total coating composition. When employed, the plasticizing agent is present in an amount from about 0.01% to about 1.0% preferably from about 0.05% to about 0.25% by weight. The balance of the composition is composed of anhydrous solvent which is preferably present from about 80% to about 98% advan- I 4 coats are sufiicient, more can be applied if desired. The coated tablets can be polished or not as desired.

The solid pharmaceutical forms which are also an important aspect of this invention are solid pharmaceutical forms such astablets, pills, pellets, troches and the like substantially completely coated with a film forming polymer containing N-vinyl-oxazolidinone as defined above. These forms are comprised of a core containing the medicament normally with a filler surrounded by said film forming polymer. The thickness of said coatings advantageously is in the range of from about .005" to about .004" preferably from about .001" to about .002". Generally it is satisfactory for the coating to be from about 0.3% to about 3% of the total weight of the tablet, preferably from about 0.5% to about 1% and as indicated above it substantially completely covers the core form. 1

Tablets coated using this procedure and coating composition yield a smooth glossy coat. The total thickness of the combined coats is such that the detail of the surface of the core is retained, for instance monograms or scores.

The followingexamples are not limiting and are used to specifically illustrate the coating composition and will make obvious to one skilled in the art the full practice I ofthe method of this invention.

tageously from 90% to about 96% by weight of the total composition.

The novel coating composition is prepared by dissolving the N-vinyl-oxazolidinone film forming polymer and when employed, the dye and plasticizer in the desired solvent. The coating composition is now ready for use and it may be poured or sprayed on the pharmaceutical forms. 7

The method of coating the solid pharmaceutical forms such as compressed tablets, pills, pellets, troches and the like in accordance with this invention comprises placing said solid forms, as the example tablets containing a medicament and filler, in a coating pan. The tablets arethoroughly and. evenly wetted with the coating solution. The tablets are dried while rotating in the coating pan. Advantageously air is passed over the tablets during the drying process. Further coats are applied by repeating the aboveprocedureL Normally lto 3 a Example 1 Ingredients: Amounts, gms.

N+vinyl-5-methyl-2-oxazolidinone copolymerized: with 50% vinyl acetate (K-value =15) 25.0 Methylene chloride 475.0 a The copolymer of N-vinyl-5-methyl 2-oxazolidinone and vinylacetateis dissolved in the methylene chloride tozform the coatingcomposition. Tablet cores of inch diameter containing chlorpromazine and fillter are placed in a rotating 12 inch .coating pan and are thoroughly and evenly wetted by spraying on the above composition. The solvent dries in several minutes leaving a hardthin coat on the tablets. A second application is applied'using approximately one-half the amount of solution that was required in the first coat and the tablets are dried while rotating with air being passed over said tablets. A third coating utilizing one-fourth of the original amount of coating solution is applied in the samemanner.

Example 2 The N-vinyl-S-methyl-2-oxazolidinone polymer is dissolved in the chloroform along with the dioctyl phthalate. Using a 12 inch coating pan the rotating tablets, with a diameter of /3 inch, containing chlorpromazine and filler are thoroughly'and evenly wetted by spraying on the above coating composition. The solvent dries in several minutes leaving a hard thin coat on the tablets. A second application is applied using approximately one-half the amount of solution that was required in the first coat and tablets are dried while rotating with air being passed over'said tablets. A third coating utilizing one-fourth of the original amount of coating solution is applied in the same manner.

v The following examples are exemplary of typical coating compositions.

Example 3 Ingredients: Amounts, gms.

5 N-Vinyl-5-methyl-2-oxazolidinone copolyrnerized with 45% vinyl acetate (K-value=25 2.00 Dioctyl phthalate 0.05 D & C yellow #11 0.40 D & C green #6 0.05 Chloroform 97.50

Dissolve the copolymerized oxazolidinone and dioctyl adipate in the acetone.

N Vinyl-5 methyl-2-oxazolidinone copolymerized with 40% vinyl acetate (K-value=20) 8.0 Dioctyl phthalate 0.1 Methylene chloride 91.

What is claimed is:

1. A film coated pharmaceutical form comprising a solid medicament containing core substantially completely surrounded by a film forming polymer containing a monomeric unit derived from N-vinyl-oxazolidinone.

2. The pharmaceutical form of claim 1 characterized in that said film forming polymer is N-vinyl-S-methyl-Z- oxazolidinone copolymerized with vinyl acetate and having a Fikentscher K-value of about 5-60.

3. The pharmaceutical form of claim 2 characterized in that said polymer has about 40-60% of copolymerized vinyl acetate and a Fikentscher K-value of about 5-25.

, 6 4. The film coated pharmaceutical form according to claim 3 further characterized in that film forming polymer coating totals from about 0.3% to about 3% of totaltablet weight and has a thickness of from about .001 to about .003.

5. A method of coating pharmaceutical forms which comprises rotating said forms in a coating pan, applying a coating composition comprising a film forming polymer containing a monomeric unit derived from N-vinyl-oxazolidinone dissolved in an anhydrous nontoxic organic solvent and drying the coated forms while continuing to rotate said forms in the coating pan.

6. The method of claim 5 characterized in that said film forming polymer has a Fikentscher K-value of from about 20 to about 40.

7. The method of claim 5 characterized in that said film forming polymer is N-vinyl-S-methyl-Z-oxazolidinone copolymerized with about 30 to about 70% of vinyl acetate and having a Fikentscher K-value of about 5-25.

8. The method of claim 7 characterized in that said coating composition contains from about 3-7% of said film forming polymer. i

9. The method of claim 8 characterized in that said polymer contains about 4060% of copolymerized vinyl acetate and has a Fikentscher K-value of about 5-25.

10. The method of claim 9 characterized in that a maximum of 3 coatings is applied.

References Cited in the file of this patent UNITED STATES PATENTS 2,805,977 Robinson Sept. 10, 1957 2,818,362 Drechsel Dec. 31, 1957 2,875,130 Grass et al. Feb. 24, 1959 2,881,085 Endicott et al. Apr. 7, 1959 OTHER REFERENCES Drug and Cosmetic Industry, article by Rowell, September 1948, pp. 308-310, 411-413. 

1. A FILM COATED PHARMACEUTICAL FORM COMPRISING A SOLID MEDICAMENT CONTAINING CORE SUBSTANTIALLY COMPLETELY SURROUNDED BY A FILM FORMING POLYMER CONTAINING A MONOMERIC UNIT DERIVED FROM N-VINYL-OXAZOLIDINONE. 